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Full text of "Effect of aggregate on shrinkage of concrete and hypothesis concerning shrinkage."

Research and Development Laboratories 

of the 
Portland Cement Association 



RESEARCH DEPARTMENT 

Bulletin 66 



Effect 



regate on Shrink- 
Concrete and Hypothesis 



Concerning Shrinka 



GERALD PICKETT 



February, 1956 
CHICAGO 



Authorized Reprint of a Copyrighted 

OUBNAL OP THE AMERICAN CONCRETE INSTITUTE 

18263 W. McNichoIs Rd., Detroit 19, Michigan 
January 1956; Proceedings Vol. 52, p. 581 



Title No. 52-36 



Effect of Aggregate on Shrinkage of Concrete 
and a Hypothesis Concerning Shrinkage 

By GERALD PICKETTt 

SYNOPSIS 

A theoretical formula is derived for effect of aggregate on shrinkage of con- 
crete during drying. Experiments designed to test the validity of the formula 

tic reported. 

In addition to indicating the validity of the formula, the data give the follow- 
ing indications: (1) First shrinkage is greater than an\ subsequent expan-mu 
or shrinkage resulting from moisture change. (2) At a given aggregate con- 
tent the shrinkage is approximately proportional to water-cement ratio (3) 
Alter hist shrinkage, subsequent volume changes are approximately inde- 
pendent of water-cement ratio. (4) When shrinkages ol specimens of the 
higher water-cement ratio are plotted against the square root of period of 
<lr\ ing, the shapes of the curves for second shrinkag( re appreciably different 
from those for first shrinkage in that they have considerable curvature uear 
the origin. An explanation of these effects is given. 

INTRODUCTION 

A number of years ago, while at the Portland Cement Assn., the author 
arrived al a theoretical formula for effect of aguregate on shrinkage of con- 
crete or mortar during drying. Experiments designed to test the validity of 
the formula gave results that were in fair agreement with the formula. How- 

er. certain factors in the formula which should depend on properties of 
the p te varied with conditions of drying and therefore led to the conclusion 
that the hydrated paste did not always have the same properties. The pur- 

p , this paper is to present the theoretical formula, experimental results 

thai were obtained, and speculations in regard to the paste that resulted from 
i Btudy of the data. 

DERIVATION OF FORMULA 

In deriving the formula, consideration is first given to effect on shrinkage 
of one small, spherical particle of aggregate in a large body of concrete, the 
surrounding concrete considered to he a homogeneous material. This ap- 
proach is similar to that of Guth 1 and Dewey,* who were concerned with 
the effect of fillers on elastic properties. The restraining effect <>f aggregate 

♦Received by the Institute Mar. 17. 19o4. Title No. 52 ifl a part of c ?hted Journal of tiif. American 

Concrete Institute. V. 27, No. 5. Jan. 1956. Proceedings V. 5-' -parate prints are availa bi oO cents each. 
DiicuMion (copies in triplicate) should reach the Institute not later than May 1. 1956. Address 18. McNicnola 

tlflember American Concrete Institute. Guest Professor of Civil Engineering. Bengal Engineering College, 
West Bengal, India. 

581 



582 JOURNAL OF THE AMERICAN CONCRETE INSTITUTE January 1956 

on shrinkage of concrete was pointed out by Carlson.' On the assumption 
that both the particle and the rest of the body are elastic, an expression is 
derived lor reduction in over-all shrinkage of the body due to the one small 
nonshrinking particle. This provides a formula for the effect of adding each 
subsequent particle if the body including all particles added previously is 
assumed to be homogeneous. This formula is then expressed n, differential 
equation form and an integration made to obtain the final formula. 

It will be expedient to consider that the small, spherical particle is at the 
center of the body of concrete which is also a sphere. If the particle is small 
compared to the shortest distance from it to the concrete surface, no great 
error will be introduced by treating the concrete as spherical with a radius 
equal to that distance. The restraint of the small sphere as the large sphere 
tends to ink will cause the following stresses in the large sphere. 4 



:i 



pa 3 b 3 — r 

Cr = ~ T 3 " b 3 - a* 



(1 



pa 3 b 3 + 2r 3 



(2) 



2 r 3 53 _ a 3 

where <r r = normal si ress in the radial direction 

a t = either oi two normal stresses pei prndicular to the radius 

r = radial coordinate 

a = radius of inner sphere 

b = radius of outer sphere 

p = unit pressure between inner and outer spheres 

Under these conditions of spherical symmetry, radial displacement 5 of any 
point in the outer sphere caused by the restraint of the inner sphere, ana 
referred to the unrestrained position, is 



r 



(3) 



(1 — /z) <*t — M°> 

where E and M are Young's modulus and Poisson's ratio, respectively, for 

the outer sphere. 

FromEq.(l), (2), and (3) 

pa 3 \~l ~ m *> 3 + 2r 3 , 6 3 - r 

e7* 



5 - 2 b 3 - a 3 + M b 3 - a J 



(4) 



Airlrb 



The restraint of the inner sphere has reduced the volume shrinkage of the 
total body by the amount 

= -fe^Z ( l - ^ db * (5) 

r = b E \ 2 )b 3 - a 3 

where AV = 4/3 ira 3 is the volume of the small sphere. 

If the restraint had not been present, the body would have reduced in 
volume by 3SY, where V is its total volume and S is the unit linear shrinkage. 
The reduction in volume shrinkage will therefore be designated as - 3a£1 , or 



- 3 A SV = - 



(6) 



E \ 2 / b 3 - a 3 

Another expression containing the pressure p will be found by considering 
the compressibility of the restraining particle. Reduction in volume of the 



EFFECT OF AGGREGATE ON SHRINKAGE 583 

particle caused by pressure p on it will be equal to the reduced space avail- 
able to it within the larger body, or 



1 - 2 M .>i>± V 

= 35 ^V - 4tt«-5 



*. 



7) 



r = a 



where E g and p g are the elastic constants of the particle and 8 is given by 
Eq. (4). 



Eliminating p between Eq. (6) and (7) and setting b/a = oo gi\ e- 



31 I - M I 



(8) 



I + m + 2i I - 2»,)E/E I 



(9 



>• ting l> <i = co will introduce an error especially for particles close to the 
surface. However, it is believed that this error is not relatively as important 
as other* entering this derivation. 

Lei volume of aggregate per unit volume of mix be g; then the increase in 
g due to the addition of one particle of volume A V to tin; mixture will be 



gV + AV AT 

Afl - ; — — -- - g = (1 - g) 



V + Al * v "' I + Al 



(10) 



From Eq. (8) and (10) 

&<s «ak r + a i 



S 1 - g 

or, m differential form, 



(II ' 



S 1 - 



12) 



The t i tor a is probably a function of y since the elastic constants ot the 
mixture. E and /x, may depend on g. But if a may be considered to be inde- 
pendent of <7, then Kq. (12) integrates to 

8 - So(l - u) a (13) 

where So is the shrinkage that would occur if no aggregate wrere pr< >nt 
I or later use this equation may be written in the form 



. ,s '° . l 

hi = Of log 



S * 1 - § 



14 



TESTS 



To test the validity of the formula. 1 x ^ x llj^-in. prism- were prepared 
with various percentages of aggregate ranging from percent to about 70 

percent by volume. Three different types of aggregate (pulverized silica, 

standard < >t!awa sand, and graded Elgin sand) were used to determine whether 
size and gradation of aggregates would also be an appreciable factor. Two 
nts. a high-early-strength and a normal, and two water-cement ratios 
were used to determine in what way the effect of aggregate might be in- 
fluenced by type of cement and water-cement ratio. 



584 



JOURNAL OF THE AMERICAN CONCRETE INSTITUTE 



January 1956 



TABLE 1— GENERAL OUTLINE OF 
CONDITIONS IN STUDY* 



Later it was decided to investigate 
reversibility of volume changes of the- 



i6ed 




Percent 
apgrega- 
bv abso- 
lute 
voluniet 



Hiiih-earl 



ica flour 



Standard Ottawa 

Ln mix sand 

Gr .1 I Band 

I ! 





5 
15 
30 



specimens. For this purpose specimens 
were alternately submerged in water 

iht an d dried in air. Each drying was 



w/c 

b\ 



end for °| 

Id was inw ftd-forn _ry 5 

, :it r,ha, 
newat <> r 1 at ?~, 

. an( j , i • ;iod was M .1 

T ,. M were n.ade 

devia- ns 
fr 



05 at 50 percent relative humidity for at 
035 least 224 days and each period of wet- 
ting was si day-. This work was be- 
guo in January, L942, and continued 

for about 2 year-. 

Table 1 gives the general outline of 
conditions covered in the study. 
Miv - containing up to 5 percent 
t«;<i re gate were too wet and those with 
mor< ■ • toodrj foi preparation of reasonably homogeneou 
] , ted n d of the position of the molds dun... setting 
some eft, ..i bleeding but many of the wet mixes were 
LU6 eoi thecoml ed effects of bleeding, shrinkage m absolute 
periodic turning i tb molds- Some drj mixes bad high 
, ,1 g h in most cases percentage oi air w kept low 

by , >u8t an The wid< mg in plastic properties ol the mixee may 

... mii iiti< in results. 



S hri nk , ng drying I - sion duriw wetting for the specimens 

, | . t, . , , ,t are show., graphicallj in Fig I and 2 

,1, , with normal a ment but are not shown. 






hrii 



ir }, curv< ras - stimated. Tin n suits are 



I le ' 



i 111 

ni . - I i </ were rciputed from Tal 2 

V to Eq n the ta hould b repr< 

t lii ii tl i " The data foi W/C ■ 

,11 i, ; ight line with a slope a eq d 

tanta in Eq. (9 would ma 

I 7 , m n that w ild gi i thi> value i* - 

0.21 

1). w/C • 0.50 'i ell •■' it w • j h 

} \u a >1« 1.7 P ■ li liefartl >m the tin* 

, ben < >ntai d a consid ibk pen 
1 1 1 1 ■ « 






li 






r 



' 









v. 



j 



I j ,d< i ih« d formul 

a. ..,i. in ! i linkage < 



■ 



iiH 



EFFECT OF AGGREGATE ON SHRINKAGE 



585 



Other ideas suggested by 
the data 

In addition to indicating 
the validity of the formula 
for the effect of assresate 



on shrinkage, the data give 
the following indications: 
(1) Fir>t shrinkage is 

greater than any subse- 
quent expansion or shrink- 
age. (2) At a given aggre- 
gate content first shrink- 
age is approximately pro- 
portional to water-cement 
ratio. (3) After first 
shrinkage, subsequent vol- 
ume changes are approxi- 
mately independent of 
water-cement ratio. (4) 
When shrinkage of speci- 
mens of the higher water- 
cement ratio is plotted 

against the square root of 
period <>i drying, the shape- 
of the curves for second 
shrinkage are appreciably 
different from those for 
first shrinkage in that they 
have considerable curva- 



ture near the origin. 

In general these four 

indications were either not 

xpected or not expected 

to the degree indicated by 

Fig. I and 2. Some of the 

change in behavior might 

have been due to carbo- 
nation during the first dry- 
ing period, but the major 
change is believed due to 
other causes, as will be 
discussed below. 






i r 



*■" -5 J* Shr -■ i 



rgofc 



A jg-e ggte . palverrzea $>?c<2 
w J. 50 




Secona 
Expansion 



Square root of dau,s exposed 



Q a 



£ SCOC 



i » 



Si S* <oge _0% aggregs+e 

5" 




- * a so^d 



*v 






E - 



Secona 
Sfi' nkage 



if 



• G 14 2 4 & 9 \2 14 

2A6G 0:4G8 



Square root cf days exposed 



c 
o 

^ 5000 
c 



■ t 



i— — « — r 



v 



St Shrink e OXpggregcte 




El gin sand 

. • 0.50 



Second 

kage 




Second 
E.xpanS'Q* 



2 



4 

2* 


2 4- S G 10 12 


14 



Square 


root of days exposed 





6 a 



Fig. 1 — Shrinkage during drying and expansion 
during wetting for pulverized silica, Ottawa sand, 
and Elgin sand using high-early-strength cement 

and W C = 0.50 



586 



JOURNAL OF THE AMERICAN CONCRETE INSTITUTE 



January 1956 



1 —I » T 1 T— T 



t r 



I « 



* 6000 

■♦- 
c 
o 

- sooo 



Pulverized silica 



f/rsf Shrinkage 



0% aggregate 



First . 
Expansion 




Second 

Shrinkage 




Second 
Expansion 



o— *-* « * » a $ E 4 6 ^ * ♦ « • » " 3 2 « « • 

Square root of days exposed 



t/> 



c 6000 
O 



£ 5000 

c 

o) 4000 

c 

u 

X 3000 

c 
u 



T r 



t 1 r 



1 r 



1 r 



Ottawa sand 
w/c * a 35 



st Shrinkage 



c 



2000 



1000 




0% aggregate 

—S.9% 

f -3% Expansion 



Second 
kage 




Secono 
Expansion-! 



6 10 12 14 Z 

2 4 6 6 

Square root of days exposed 



z 



4 6 6 



v» 



1 1 



t 1 T P 



T f ' P 



.9 5000 

1 

•£ 4000 



w/c ' a 3s 



c 

X 

u 

c 
u 



3000 



Z000 



1000 



First Shrinkage q% aggregate 

HAIL F ' rSt 

_„_ 6 * Expansion 




Second 
' nnuaae 



Secor 
t> portion 



C Z 



6 



Square root of days exposed 



Fig. 2 — Shrinkage during drying and expansion 
during wetting for pulverized silica, Ottawa sand, 
and Elgin sand using high-early-strength cement 

and W C = 0.35 



HYPOTHESIS ON GEL 
STRUCTURE 

As a basis for an expla- 
nation it is proposed (1) 
that during first shrinkage 
some adjacent particles of 
the cement gel move closer 
together, whereas others 
move farther apart, and 
(2) that, in general parti- 
cles that have once made 
close contact will not re- 
turn to their original rela- 
tive positions with sub- 
sequent wetting. 

No definite picture of 
gel structure before fir 
shrinkage is required for 
this analysis except that 
the gel be slightly altered 
by the first shrinkage. As 
water is removed, inter- 
particle forces will change, 
necessitating relative 
movements between parti- 
cles for equilibrium of indi- 
vidual particles, [f thes< 

relative movements for 

each pair of particles are 
not in proportion to the 

original distances between 

their centers, the arrange- 
ment will be ni idered to 
have changed. 



If only discrete colloidal 

were present, 

of hydra ted 

cement might be mor- 
nearly like that of soil 

and show a shrinkage limn 



particles 

shrinkage 



EFFECT OF AGGREGATE ON SHRINKAGE 



587 



TABLE 2 



FREE SHRINKAGE OF SPECIMENS OF VARIOUS PERCENTAGES 

OF AGGREGATE 



Absolute 
volume of 
aggregate 

per 
mix volume 


Shrinkage in imlhunths 


First shrinkage 


Second shrinkage 


Silica 


Ottawa 
sand 


Elgin 
sand 


Silica 


Ottawa 
sand 


Elgin 

sand 



W/C = 0.50 






5870 


5870 


5870 


2180 


2180 


2180 


0.05 


4000 


5450 


5350 


17 JO 


2100 


2100 


0.15 


3600 


4500 


3720 


1.530 


1600 


1500 


0.30 


2200 


2850 


2700 


950 


1100 


1100 


0.50 


_'( >00 


1700 


1650 


710 


670 


640 


0.67 




m— 


890 


^^^™ 


^^■^^ 


410 









W C = 0.35 











3700 


3700 


3700 


2050 


2050 


21 '.".0 


0.06 


3230 


3450 


3380 


1700 


1750 





0.18 


2410 


2720 


2690 


1300 


1 380 


1430 


0.34 


— 


1800 


1810 


— 


moo 


1000 


0.53 




\*W 


1080 


— 


">10 


620 


0.62 






900 






300 



i.e., down to some limiting shrinkage, it would show a shrinkage in volume 
i-ninparable to the volume of water lost. However, in concrete, restraining 
bodies act from the beginning of drying to reduce shrinkage. 3 The restrain- 
ing bodies are the aggregates, unhydrated cemenl grains, and staUe micro- 
crystalline products of hydration. There would, of course, be some differ- 






'/> 



o 



. 



I 



0.8 _ 



C-6 



0.4 



0.2 - 



3.0 



_D 



0.0 



loq§2 = a\oq . — 




0C=I.7- A / w/c=0.35 




• - 


l st Pulverized Silica 


O - 


2 nd n •' 


A - 


i st Ottawa Sand 


A - 


2 nd l% • 


» - 


1 st Elgin Sand 


n - 


2nd h « 



0.2 



0.4 



0.6 



0.0 



0-2 



0.4 



0.6 



0.8 



og 



i-g 



Fig. 3 — Effect of aggregate on shrinkage 



588 



JOURNAL OF THE AMERICAN CONCRETE INSTITUTE January 1956 

ence in the intrinsic shrinkage of cement gel and soil because of the bonds 
between p'-l particles. Experiments show that concrete shrinkage instead of 
being about equal to volume of water lost is ordinarily only about 2 to J per- 
cent as much. When shrinkage is not equal to loss of water, .space. will 
form and hydrostatic tension must result, A given ge particle will be under 
tensile for, ,. tending to pull it toward adjacent particles These forces may 
be intense, as is shown below by the relation between hydrostatic tension 
and relative humidity. Under the conditions for which Kelvin s equation 
for the curvature of a meniscus in equilibrium with its vapor applies, the 
intensity ot hydrostatic tension of water at room temperature is given by 

r = - 19,600 log, h 
where T = hydro 'tic tension in psi 

h = relative humidity 

For example, if h = 0.98, T = 392 psi and if h = 0.50, T = 13,600 psi. 
Kelvin's equation probably is not applicable when radius of curvature is 
onlv a few molecular diameters. 

Under the action of forces of hydrostatic origin some adjacent particles 
will U pulled or pushed closer together while other adjacent particles will be 
pull, farther apart. As two adjacent particles are brought closer together, 
large compressive forces at the points of closest approach will naturally 
arise from inter molecular repulsion. These compressive forces should in- 
crease with increase in nearby tensile forces so that the particle, remain m 

equilibrium. As a result of high contact pressures, the particles will 
probablv develop chemical or surface bonds which will tend to prevent future 
separation of particles, even after hydrostatic tension has been decreased by 
increase in water content. 

The above considerations lead to the conclusion that the first shrinkage al- 
tei s gel structui so as to change size distribution of spaces between partial 
Larger sp es will become larger and smaller ones will become smaller De- 
nse in general those particles that were closest to each other are brought 
even Los< r together and those particles that were separated by larger spaces 
are p lied farther apart. In this analysis it is not necessary to decide whether 
the spaces under consideration are the capillary spaces or the much smaller 
gel pores or both. If the spaces are capillary spaces, then the word ''particle" 
refers to the capillary walls rather than to individual gel particle,. 

Application of the hypothesis to test results 

The first shrinkage is greater than any subsequent expansion or shrinkage 
(indi. tion 1. p. 585) because the arrangement of gel particles and groups oi 
gel particles is changed during first shrinkage. At a given aggregate content 
the extent of first shrinkage should increase with increase in water-eemen 
rati«» indication 2. p. 585). The original spacing of cement grains depend 
on the water-cement ratio and therefore th< iverage spacing of the gel ir- 
ticles in their first arrangement should al,o depend on water-cement ratio. 
Mon motion during first shrinkage is possible with greater spacing. 



EFFECT OF AGGREGATE ON SHRINKAGE 589 

After the first shrinkage subsequent volume changes are approximately in- 
dependent of water-cement ratio (indication 3, p. 585) because after once 
having been dried the spacing between adjacent gel particles should be more 
a function of humidity and of the corresponding degree of drying than of origi- 
nal spacing. The gels from mixes of higher water-cement ratio will have a 
more open structure between agglomerations of particles but not necessarily 
any greater capacity for changes in volume. This last statement is in accord 
with the conception of gel structure given by Powers. On the basis of various 
experiments he concludes that the gel substance has a characteristic spacing 
of the gel particles. 56 - 7 

The difference in shape of the curves for first and subsequent shrinkages 
(indication 4, p. 585) is attributed to both the change in distribution of cap- 
illary sizes and to the fact that stabilization takes place during first shrink- 
age but does not occur appreciably during subsequent shrinkages. In any 
given region in the specimen most of the water in the larger capillaries must 
be lost before appreciable hydrostatic tension can be developed. During 
the first shrinkage, before gel structure has become stabilized, appreciable 
shrinkage can take place with little hydrostatic tension. But after the gel 
lias become stabilized, larger interparticle forces are required to produce 
comparable shrinkages. The pastes of lower water-cement ratio do not have 
many large capillaries and therefore, in drying, soon reach the linear portion 
of the shrinkage versus square-root-of-time relation even though the gel 
has been stabilized. Moreover, the gels in pastes of low water-cement ratio 
undergo relatively little structural change during first shrinkage because of the 
original close particle spacing. 

From the above picture it would appear that all volume changes after the 
first shrinkage should be fairly reversible; however, shrinkage stress- result- 
ing from nonuniform drying or wetting and chemical changes will no doubt 
cause some change in the structure and therefore prevent complete reversi- 
bility. 

Explanation of plastic properties of hardened concrete 

As noted by many investigator concrete has the capacity for a com- 
paratively large amount of creep and the apparent rate of creep for a given 
stress is relatively large if loads are applied during drying. Although an 
attempt was made in an earlier paper 8 to show that at least a part ot this 
effect was a natural consequeme of nonuniform shrinkage and a nonlinear 
stre,s-creep relationship, no satisfactory explanation has been given for the 
large capacity for creep without failure in tension (cracking) that concrete 
has while drying as compared to its smaller capacity for creep before or after 

drying. 

By assuming that gel particles change their relative positions, some making 
closer contacts and others separating during drying, we can understand 
the large capacitv for creep which concrete has while drying. The picture 
is that each small community of particles will undergo considerable distor- 



590 JOURNAL OF THE AMERICAN CONCRETE INSTITUTE January 1956 

tional deformation. However, because these deformations are miscellaneously 
orientated, a region consisting of many such small communities will ap- 
parently have no distortion. But if a small stre in a given direction is 
added, the region will have a resultant distortion which could be of con- 
siderable magnitude if high interparticle stresses are also present. After the 
gel particles have acquired stable positions, the rate of creep will be much 
less for a given stress and the capacity for creep will be materially reduced, 
for the action just described cannot take place. 

ACKNOWLEDGMENTS 

Except for minor revisions, this paper was written in 1944 while the author 
was at the Portland Cement Assn. working under the direct supervision of 
T. C. Powers. Credit is due Air. Powers and' the Portland Cement Assn. 
not only for the work here reported but for urging that the paper be submitted 
lor publication. 

REFERENCES 

1. Gutli. E., 'Theory of Filler Reinforcement," Journal of Applied Physics, V. 16, Jan. 

1945, p. 20. 

2. Dewey, J. M., "Elastic Constantsof Materials Loaded with Xon-Rigid Fillers,' 1 Journal 

of Appl I Physics, Y. 18, June 1947, pp. 578-581. 

3. Carlson, l: W., Drying Shrinkage of Laiu<' Concrete Members," ACI ■!"• enal, .Jan - 

1 t>. L937, Proc. V. :«, \>. -. 

I. Timoslu ■), S., and Goocli I \'., Theonj of Elasticity, 2nd Edition, McGraw-Hill 

Book Co., Inc.. \ T ew York. L951, p. 359. 

5 Powers, T. C, and Brownyard, T. L., "Physical Properties of Hardened Portland 
Cem. ,,t Paste,' ACI Journai . Feb. 1947, Proc. V. 43, pp. 495 and 704-7(M>. 

6. Powers, T. C, \ Working Bypothesis for Further Studies of Frost Resi>i:mce of Con- 
r VCIJ cjrnal, Feb. 1945, Prac. V. 41, p. 246. 

7 Powers, T. C, and Helmutli II \., "Theory of Volume Chang' - in Hardened Portland 
Cement Pas 1 i luring Freezing Proceed is, Highway Research Hoard, V. :\2, L953, p. 285. 

8. Pickett, G., 'I be Effect oi Moisture Content on the Creep of Concrete under a Sus- 
tained I l \CI Joui w,, Feb. 1942, Proc. V. 38, p. 333. 

For such discussion of this paper as may develop please see Part 2, 
December 1956 Journal. In Proceedings V. 52 discussion immediately 
follows the June 1956 Journal pages. 



Bulletins Published by the 

Research Department 

Research and Development Division 

of the 

Portland Cement Association 



Bulletin 1 



If 



Estimation of Phase Composition of Clinker in the System 
SK) 2 -2CaO SH):-3CaO AM> 3 -4CaO AU0 3 Fei0 3 at Clinkering T 

attires," bv L. A. Dahl, May, 1939. 

■v, o. .., *i **\ if. \r.. 11 I'). 1 



3CaO 
Temper- 



Reprinted from Rock Products, 41, No. 9. 48; No. 10, 46; N 
(1938J; 42, No. 1, «8; No. 2, 46; No. 4, 50 (1939). 



11, 42; No. 12. 44 



Bulletin 2 



Bulletin 3 



"The Bleeding of Portland Cement Paste, Mortar and Concrete Treated 
as a Special Case of Sedimentation," by T. C. Powers; with an appendix 

by L. A. Dahl; July, 1939. 

-"Rate of Sedimentation: I. Nonflocculated Suspensions of Uniform 
Spheres; II. Suspensions of Uniform-Size Angular Particles; III. 
Concentrated Flocculated Suspensions of Powders ; by HAROLD H. 

Steinour, October, 1944. 

Repi inted from Industrial and Engirt Chemistry, 36, 018, 840, 901 (1944). 

Bulletin 4— "Further Studies of the Bleeding of Portland Cement Paste," b> 11 vitoi i> 

H. Steinoi k, December, lul.">. 



Bulletin 5 



Bulletin 5A 



Bulletin 6 



Bulletin 7 



Bulletin 8 



Bulletin 9 



Bulletin 10 



Bulletin 11 



"A Working Hypothesis for Further Studies of Frost Resistance of 
Concrete," bv T. (.'. POWERS, February, U»4. r >. 

Reprinted from Journal of the American Concrete Inetitute (February, 1045); Pro- 
ceeding* 41, 245 (1945). 

Supplement to Bulletin 5; Discussion of the paper "A Working Hy- 
pothesis for Further Studies of Frost Resistance of Concrete, by 

T C Powers; discussion by: Ruth D. Tbrzaghi, hm ,,, as M. Henry, 
H W Brewer, A. R. Collins, ami Author; March, 1946. 

Reprinted from Journal of the American Co He Inst, t Supplement (November 
1945); Proceedinus, 41. 272-1 L945). 

"Dynamic Testing of Pavements," by Cerai u Pl< mm. ^pril, 1946 

Uepri..te<l fro.,. Journal of the American C rete Instituti April. 1945); Proceeding*. 

41, 473 (1945). 

-Equations for Computing Elastic Constants from F, * xu /^*£* tor- 
sional Resonant Frequencies of Vibration of Prisms and Cylinders, 
by Gerald Picxett, September, 194;). 

Reprinted from Proceedings, Am, eon Society for 3 ling M atenah 45,848 194 

discussion, 864. 

-"Flexural Vibration of Unrestrained Cylinders and Disks," bv Gerald 
Pkkett, December, 1 ( .)4">. 

Reprinted from Journal of Applied Physics, 16, 820 1 1945). 

--Should Portland Cement Be Dispersed?" by T. C. Powers, February, 

1 ( )40 

Reprinted from Journal of the Am an C rete Ins* November. 1945); Pro- 

ceedings,^, 117 (1946). 

-"Interpretation of Phase Diagrams of Ternary Systems," h> L, A. Dahl, 

March, 1946. 

Reprinted from Thi Journal of Physical Chemistry, 50, M (1946). 

--Shrinkage Stresses in Concrete: Part l-Shrinkage or Swelling 
Its Effect upon Displacements and Stresses in Slabs and Beams of 
Homogeneous, Isotropic, Elastic Material; Part 2 -Appl.ca .on of he 
Theory Presented in Part 1 to Experimental Results ; bv GBHALD 
Pickett, March, 1946. 

Reprinted from Journal of the American Concrete Institute January and February, 
1946); Proceedinge, 42, I- (61 (1946). 



Bulletin 12 



Bulletin 1£ 



Bulletin 14 



Bulletin 15 



Bulletin 16 



Bulletin 1 ~ 



Bulletin I 



Bulletin 19 



Bulletin 20 



Bulletin 21 



Bulletin 22 



Bulletin 2 



Bulletin 2 



Bulletin 25 



"The Influence of Gypsum on the Hydration and Properties of Portland 
Cement Pastes," by William Lerch. March, 1946. 

Reprinted from Proceedings. American Society for Testing Materials, 46. 1251 (1946). 

"Tests of Concretes Containing Air-Entraining Portland Cements or 
Air- Entraining Materials Added to Batch at Mixer," by H. F. Goxxer- 
iian, April, 1947. 

Reprinted from Journal of A xer. i Concrete Institute (June. 1944': Proceedings, 
40 477 (1944 ; also supplementary data and analysis, reprinted from bupplement 
(November. 1944 ; Proceedings. 40. 508-1 <1944). 

"An Explanation of the Titration Values Obtained in the Merriman 
Sugar-Solubility Test for Portland Cement," by William Lerch. 
March. 1947. 

Reprinted from ASTM Bulletin. No. 145. 62 March. 1947). 

"The Camera Lucida Method for Measuring Air Voids in Hardened 
Concrete," by George J. Verreck. May, 1947. 

Reprinted from Journal of American Concrete Institute (May. 1947); Proceedings, 
43. 1025 (1947). 

"Development and Studv of Apparatus and Methods for the Determina- 
tion of the Air Content of Fresh Concrete," by Carl A. Menzel, May. 
1947 

Reprinted from Journal of the American Concrete Institute (May, 1947 ; Proceedings. 
43, 1053 (1947). 

"The Problem of Proportioning Portland Cement Raw Mixtures: 
Part I— A General View of the Problem; Part II— Mathematical Study 
of the Problem; Part III— Application to Typical Processes; Part I\ — 
Direct Control of Potential Composition"; by L. A. Dahl, June, 1947. 

Reprinted from Rock Products. 50. No. 1 109; No. 2, 107; No. 3. 92. No. 4. 122 (1947). 

"The System CaO-SiO.-H O and the Hydration of the Calcium Sili- 
cates," by Harold H. Steixolr, June, 1947. 

Reprinted from Chemical Reviews, 40. 391 T'47). 

"Procedures for Determining the Air Content of Freshly-Mixed Con- 
crete by the Rolling and Pressure Methods," by Cam V. Menzel, 

June, 1947. 

Reprinted from Proceedings. American Society for Testing Materials. 47, 833 <1947). 

"The Effect of Change in Moisture-Content on the Creep of Concrete 
under a Sustained Load," by Gerald Pi< kett, July, 1947. 

Reprinted from Journal of the American Concrete Institute (Februar\. iy42); Pro- 
ceedings. 38, 333 (1942). 

Effect of Gypsum Content and Other Factors on Shrinkage of Concrete 
Prisms,'* by Gerald Pickett, October, 1*47. 

Reprinted from Journal of the American Concrete Institute (October. 1947); Pro- 
ceedings, 44. 149 (1948). 

Studies of the Ph\sical Properties of Hardened Portland Cement 
Paste," by T ( . Powers and T. L. Brown yard, March, 1948. 

Reprinted from Journal of the American Concrete Institute (October-December. 1946; 
January-April. 194 1 ; Proceeding -H. 101 24'». 469, 549, 669. 845, y33 1 1947). 

"Effect of Carbon Black and Black Iron Oxide on Air Content and Dura- 
bility of Concrete," I y Thomas G. Tayi.or. May, 1*.*4S. 

Reprinted from Journal of thf A m Concrete Institute (April, 1948); Proceeding*, 

44, 613 (1948 

Effect of Entrained Air on Concretes Made with So-Called Sand- 
Gravel' Aggregates/' by Paul Klieger, November, 1 ( j48. 

Reprinted from Journal of the American Concrete Institute (October. 1948 » Pro- 
ceedings), 45, 149 1949). 

4 A Discussion of Cement Hydration in Relation to the Curing of Con- 
crete/' by T. C Power- August, 1948. 

Reprinted from Proceedings of the Highway Research Board, 27, 178 (1947). 



Bulletin 2t> 



i . 



1 'Long-Time Study of Cement Performance in Concrete/* This bulletin 
comprises four installments of the report of this investigation, by F. R. 
McMillan, L L. Tyler, W. C Han-en. William Lerch, C. L. Ford, and 
L S Brown. August, 1948. 

Reprinted from Journal of the Amerxcan Concrete Institute February-May. 1948 
Proceedings . 44. 441 553 743. 877 (1948). 



27 



Bulletin 28 



Bulletin 



"Determination of the Air Content of Mortars by the Pressure Method," 

by Thomas G. Taylor, February, 1949. 

Reprinted from ASTM Bulletin, No. 155. 44 (December. 1948). 

"A Polarographic Method for the Direct Determination of Aluminum 
Oxide in Portland Cement," bv C. L. Ford and Lorratne Le Mar, 
April, 1949. 

Reprinted from ASTM Bulletin, No. 157, 66 (March. 1949). 

"The Nonevaporable Water Content of Hardened Portland-Cement 
p aste — Us Significance for Concrete Research and Its Methods of 
Determination," by T. C. Powers, June, 1949. 

Reprinted from ASTM Bulletin, No. 158. 68 (May. 1949). 

Bulletin 30— "Long-Time Studv of Cement Performance in Concrete— Chapter 5. 

Concrete Exposed* to Sulfate Soils," by F. R. Mi Millan, T. E. Stanton. 
I. L. Tyler and W. C. Hansen, December, 1949. 

Reprinted from a Special Publication of the American Concrete Institute (1949). 

"Studies of Some Methods of Avoiding the Expansion and Pattern 
Cracking Associated with the Alkali-Aggregate Reaction," by William 
Lerch, February, 1950. 

Reprinted from Special Technical Publication No. 99, published by American Society 
for Testing Materials (1950). 



Bulletin 31 



Bulletin 32 



Bulletin 33 



"Long-Time Study of Cement Performance in Concrete— Chapter 6. 
The Heats of Hydration of the Cements," by George J. Verbeck and 
Cecil W. Foster, October, 1949. 

Reprinted from Proceedings, American Society for Testing Materials, 50, 1235 (1950). 

"The Air Requirement of Frost-Resistant Concrete," by T. C. Powers; 
discussion bv T. F. Willis. 

Reprinted from Proceedings of the Highway Research Board, 29, 184 (1949). 



Bulletin 34 



t * 



Bulletin 35 



Bulletin 36 



Bulletin 37 



"Aqueous Cementitious Systems Containing Lime and Alumina, 

by Harold H. Steinour, February, 1951. 

"Linear Traverse Technique for Measurement of Air in Hardened 
Concrete," by L. S. Brown and C. U. Pierson, February, 1951. 

Reprinted from Jovrnal of the American Concrete Institute (October, 1950); Proceed- 
ings, 47, 117 (1951). 

"Soniscope Tests Concrete Structures," by E. A. Wmitbhi rst, February, 
1951 

Reprinted from Journal of the American Concrete Institute (February, 1951); Pro- 
ceedings 47, 433 (1951). 

"Dilatometer Method for Determination of Thermal Coefficient of 
Expansion of Fine and Coarse Aggregate," by Georoe J. Verbeck and 
Werner E. Hass, September, 1951. 

Reprinted from Proceedings of thi Highway Research Board, 30, 187 (1951). 

Bulletin 38-"Long-Time Study of Cement Performance in Concrete— Chapter 7. 

New York Test Road," by F. H. Jackson and I. L. 1 tler, ( tetober, 19ol. 

Reprint* <1 from Journal of the American Concrete Institute (June. 1951 Proeeedxngt 
47, 773 (1951). 

"Changes in Characteristics of Portland Cement as Exhibited by Lab- 
oratory Tests Over the Period 1904 to 1950," by H. \. Gonnerman and 
William Lerch. 

Reprinted from Special Publication No. 127 pubh-hed b> American Society for Testing 

Materials. 

-"Studies of the Effect of Entrained Air on the Strength and Dura- 
bility of Concretes Made with Various Maximum Sizes of Aggregate, 

by Paul Klieger. 

Reprinted from Proceedings of the High\ Research Board, 31, 177 1 - 

Bulletin 41— "Effect of Settlement of Concrete on Results of Pull-Out Bond Tests," 

by Carl A. Mexzel, November, 1952. 



Bulletin 39 



Bulletin 40 



* i 



Bulletin 42 



II 



An Investigation of Bond Anchorage and Related Factors in Rein- 
forced Concrete Beams," by Carl A. Menzel and William M. Wood-. 
November, 1952. 



Bulletin 4*-"Ten Year Report on the Long- lime Muav 01 umeni renuruiau,., 

in Concrete. •• bv Advisory I .mmittee of the Long-Time Study of Cement 
Pen'ornianc n ( acrete, R. F. Blanks, Chairman. 

Reprinted from Journal of the American Concrete Ins: March. 1953) ; Proceeding*. 

49. 601 (1953). 

Bulletin 44— "The Reactions and Thermochemistry of Cement Hydration at Ordi- 
nary Temperature." by Harold H. SteinoTr. 

Reprinted from Third International S ponum on the Chemistry of Cement. London. 
Sept. 1952. 

Bulletin 4^— "Investigations of the Hydration Expansion Characteristics of Portland 

Cement. "• y H. F. Gonnbbma Wu. Ler. h. and Thoma- ML Uhitesidl 
June, 1953. 

Bulletin 46— "Theorv of Volume Changes in Hardened Portland Cement Paste 

During Freezing." by T. C. Powers and R. A. Helmuts. 

Reprinted from Proceedings of the Highway Research Board, 32 285 (1953). 

Bulletin 47— The Determination of Non-Evaporable Water in Hardened Portland 

Cement Paste," b L. E. Copeland and John < Hayes 

Reprinted fron - TM Bulletin So. 194. "0 (December. 1953). 

Bulletin 48— The Heats of Hydration of Tricalcium Silicate and beta-Dicalcium 

Silicate." by Stephen BRr.wu.-ER. T - C. Hates and W. r Ha- 

Reprinted from The Journal of Physical C'.emistry. SB. - ^ 1954). 

Bulletin 49 — "Void Spacing as a Basis for Producing Air-Entrained Concrete, 

by T. C Power- 

Reprinted from Journal of the American Concrete Institute May. 1954). Proceedings. 

50. 741 (1954). 

Bulletin 4*) A— Discussion of the paper "Void Spacing as a Basis for Producing Air- 
Entrained Concrete," by J. E. Bacestrom. EL W. Burrows, \ E. \\ olx.- 

odoff and . jthor. T. C Power- 

Reprinted from Journal of the American Concrete Institute (Dec.. Part 2 I Pro- 

ceedings, 50 760-1 

Bulletin 50 — "The Hydrates of Magnesium Perchlorate by L. E I pelaxd and R. 

H. Bragg. 

Reprinted from The Journal of Physical Chemistry 58. 1075 (1954 

Bulletin 51 — "Determination of Sodium and Potassium Oxides in Portland Cement 

Raw Materials and Mixtures, and Similar Silicates by Flame Photom- 
em ." by C. L. 1 rd. 

Reprinted from A nalytical Chemistry 4b 1578 1954 

Bulletin 52— "Self Desiccation in Portland Cement Pastes/' I L E. Cupelaad and 

Pi. H. Bragg. 

Reprinted from AS TM Bullet. N'o. 204 34 February. 1 Vl - 



Bulletin 53 — "Permeability of Portland Cement Pastes." by T.< • >wers L E Com 

l V I Bates and H. M. M \ 

Reprinted fit: Journal of th* American Concrete Insttiu November. 1954 Pro- 

ceeding*, 51 - (W - 

Bulletin 54 — "Some Observations on the Mechanics of Alkali- Aggregate Reaction," 

bv L S Brown 

Reprinted from ASTSi Bui No. 205 40 April. 1955). 

Bulletin 55— Wn Interpretation of Published Researches on the Alkali-Aggregate 

Reaction: Part 1 — The Chemical Reactions and Mechanism of Expan- 
sion; Part 2 — A Hypothesis Concerning Safe and Unsafe Reactions 
with Reactive Silica in Concrete," Powers and H . H ? ei> "R. 

% 

Reprinted from Journal of U \meriem ncret I istitu February and April. 1955 
Proceeding* 51 " 'So 

Bulletin 56 — 'Comparison of Results of Three Methods for Determining Young - 

Modulus of Elasticity of Concrete/' by H. 1 Philleo. 

R -in ted from J jwnud o. -tricar. mcrei* InMitule (January. I Proce* 

51 461 



Bulletin 57 



"Osmotic Studies and Hypothesis Concerning Alkali- Aggregate Re 
action," by ( rEORGE J. Verbeck and Charles Gramlich. 

Reprinted from Proceedings, American. Society for Testing Material*, 55, (1955). 



Bulletin 58— "Basic Considerations Pertaining to Freezing and Thawing Tests," by 

T. C. Powers 

Reprinted from Proceedings, American Society for Test Materials, 55, (l<~>v. 

Bulletin 59— "New Study on Reactions in Burning Cement Raw Materials," by 

L. A. Dahl. 

Reprinted from Rock Product*, 58, No. 5, 71; No. 6, 102; No. 7, 78 (1955). 

Bulletin 60— "Long- Time Study of Cement Performance in Concrete— Chapter 9. 

Correlation of the Results of Laboratory Tests with Field Performance 
Under Natural Freezing and Thawing Conditions," by F. H. Jackson. 

Reprinted from Journal of th I »,. an Com n '• Institute (October. 1955); Proceedings 
52, 159 (1956). 



Bulletin 61 



Bulletin 62 



-"A Method for the Determination of the Cement Content of Plastic 
Concrete," by W. G. Himk and R. A. \\ ii.i.i.s. 

Reprinted from ASTM Bulletin No. 209. 37 (October. 1955). 

-"Investigation of the Franke Method of Determining Free Calcium 
Hydroxide and Free Calcium Oxide," by E. E. Pressler, Stephen Bri - 

naier ami 1). L. Kani m>. 

Reprinted from Analytical Chemistry, Vol. 00, p. 00, 1955. 

Bulletin 63— "Hydraulic Pressure in Concrete," by T. C. Powers. 

Reprinted from Proceeding* Ami lean Society of C - 81,74.' July, 1955 



Bulletin 64 



Bulletin 65 



Bulletin 66 



"The Freezing and Thawing Test," by T. C. Pow i rs 

Reprinted from ASTM R< port on Significance of Tests of Cor • ncrete Aggre- 

gates frd. Edition, 1955. 

'The Stoichiometrv of the Hydration of Tricalcium Silicate at Room 
Temperature: I— Hydration in a Ball Mill; II— Hydration in a Paste 
Form," bv Stephen I'.kinu iii, L. E. Copeland and R EJ. Bragg. 

Reprinted from Th, Journal o) Pi col Chem > Vol. 60 p. 112 (January, 1" 

"Effect of Aggregate on Shrinkage of Concrete and Hypothesis Concern- 
ing Shrinkage, "by Gerald Pickett. 

Reprinted from Journal of th< biw Concrete Institu (January, 1956); Proceed- 

ings, 52, p. 581 1 1956).